Publications by authors named "Zhicen Lu"

Background: This study aimed to explore the effects of the titanium dioxide (TiO) concentration and particle size in hydrogen peroxide (HP) on tooth bleaching effectiveness and enamel surface properties.

Methods: TiO at different concentrations and particle sizes was incorporated into 40% HP gel to form an HP/TiO gel. The specimens were randomly divided into 8 groups: C1P20: HP + 1% TiO (20 nm); C3P20: HP + 3% TiO (20 nm); C5P20: HP + 5% TiO (20 nm); C1P100: HP + 1% TiO (100 nm); C3P100: HP + 3% TiO (100 nm); C5P100: HP + 5% TiO (100 nm); C0: HP with LED; and C0-woL: HP without LED.

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Statement Of Problem: While repurposing waste materials into zirconia blocks presents a promising avenue, uncertainty remains regarding whether the bonding properties of recycled zirconia align with those of commercially available zirconia.

Purpose: The purpose of this in vitro study was to evaluate the bonding affinity and durability of composite resin to recycled zirconia.

Material And Methods: A series of processing steps were performed with recycled zirconia residuals (Lava Plus; 3M Oral Care), including pulverization, sieving, heating, compaction, isostatic pressing, and presintering.

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Statement Of Problem: While waste zirconia can be recycled, whether the optical properties of recycled zirconia match those of commercially available zirconia is unclear.

Purpose: The purpose of this in vitro study was to evaluate the optical properties of recycled zirconia by assessing its color, translucency, and opalescence across different thicknesses and shades.

Material And Methods: Sixty specimens were prepared from 3 mol% yttria-stabilized tetragonal zirconia polycrystal blocks (Lava Plus; 3M ESPE) (group C); 60 other specimens were prepared from waste blocks of the same zirconia (group R).

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This in vitro study aimed to determine the optimal frequency and energy settings for debonding zirconia restorations using an erbium-doped yttrium aluminum garnet (Er:YAG) laser. A total of 200 zirconia specimens (5 mm × 5 mm × 1.5 mm) were fabricated from two types of materials: (1) 3 mol% yttria oxide stabilized tetragonal zirconia polycrystalline (3Y-TZP) and (2) 5 mol% yttria oxide stabilized tetragonal zirconia polycrystalline (5Y-TZP).

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Cathepsin K (catK) modulates the degradation of dentin collagen. This study aimed to evaluate the effects of catK inhibitors on dentin erosion. Dentin beams were eroded (4 times/d for 5 days) and immersed in deionized water (negative control), 0.

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Purpose: To investigate the bond durability of composite cement to zirconia after treatment with a 15-methacryloyloxypentadecyl dihydrogen phosphate (15-MPDP)-containing adhesive and 2 commercially available adhesives.

Materials And Methods: Ninety zirconia bars were fabricated and bonded to prepolymerized resin composite cylinders with a composite cement after surface treatment for 20 s using the following adhesives: Adper Easy One (AEO, negative control), Single Bond Universal (SBU, positive control), and 10 wt% 15-MPDP powder mixed with Adper Easy One (15- MPDP). After storage in distilled water at 37°C for 24 h, the specimens were divided into 3 subgroups according to the aging treatment applied (n = 10): no aging treatment (0/TC), 10,000 thermocycles (1/TC), and 37,500 thermocycles (3/TC).

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This in vitro study aimed to investigate the effect of quercetin pretreatment on the bond strength of bleached dentin. Human dentin blocks (2 × 2 × 1 mm) were prepared and randomly divided into 5 groups (n = 16): deionized water pretreatment + no bleaching treatment (DNB); deionized water pretreatment + bleaching treatment (DYB); 75 μg/mL quercetin pretreatment + bleaching (Q75B); 150 μg/mL quercetin pretreatment + bleaching (Q150B); and 300 μg/mL quercetin pretreatment + bleaching (Q300B). The surfaces of superficial dentin (bonding surfaces) were treated with the respective solutions for 2 min, and then the surfaces opposite to the bonding surfaces (near pulp, bleaching surfaces) were subjected to bleaching treatment with 40% hydrogen peroxide (Ultradent, USA) for two 15-min sessions (groups DYB, Q75B, Q150B, and Q300B).

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This in vitro study used the same frequency and duration of acid contact as a previous in situ/in vivo study to evaluate the effect of erosion on CAD/CAM restorative materials and human enamel and to compare the effects of in vitro and in situ/in vivo acid challenges on CAD/CAM restorative materials and human enamel. The CAD/CAM restorative materials (IPS e.max CAD, Lava Ultimate, and PMMA block) and human enamel were eroded by immersion in 150 ml of cola drink for 14 days (4 × 5 min/day).

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Purpose: Shear bond strength (SBS) test is the most commonly used method for evaluating resin bond strength of zirconia, but SBS results vary among different studies even when evaluating the same bonding strategy. The purpose of this study was to promote standardization of the SBS test in evaluating zirconia ceramic bonding and to investigate factors that may affect the SBS value of a zirconia/resin cement/composite resin bonding specimen.

Materials And Methods: The zirconia/resin cement/composite resin bonding specimens were used to simulate loading with a shear force by the three-dimensional finite element (3D FE) modeling, in which stress distribution under uniform/non-uniform load, and different resin cement thickness and different elastic modulus of resin composite were analyzed.

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Objectives: To examine effectiveness of pre-silanization in improving bond performance of multipurpose products such as universal adhesives or self-adhesive resin cements to silica-based ceramics.

Methods: The present study investigated reactions between silanol groups of γ-methacryloxypropyltrimethoxysilane (γ-MPS) and silica, dehydration self-condensation of γ-MPS, and condensation polymerization between γ-MPS and 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) by using thermodynamic calculations. Shear bond strength (SBS) tests were used to evaluate the influence of pre-silanization on resin bonding when a silane-containing universal adhesive, a silane-unknown universal adhesive, or two self-adhesive resin cements were applied for bonding lithium disilicate to resin.

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Objectives: To examine whether solvents and changing the molecular structure of 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) affect its chemical affinity to Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP).

Methods: The present work investigated the chemical affinity between Y-TZP and 10-MDP dissolved in different solvents (acetone/ethanol/water or mixture) using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and thermodynamic calculations. Shear bond strength (SBS) tests were used to evaluate the influence of different solvents on 10-MDP bonding.

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Purpose: To test the hypothesis that the concentration of 10-methacryloxydecyl dihydrogen phosphate (MDP) in zirconia primers has no effect on the chemical bonding efficacy of methacrylate resins to yttria-stabilized tetragonal zirconia (Y-TZP).

Materials And Methods: Shear bond strength testing was performed to evaluate the efficacy of experimental primers containing 5, 10, 15, 20 or 30 wt% MDP (5M, 10M, 15M, 20M, 30M) in improving composite-zirconia bond strength. Bonding without use of MDP-containing primer served as the negative control (Ctr0).

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Objective: To analyze chemical mechanism of bonding improvement of zirconia via 10-methacryloyloxydecyl dihydrogen phosphate (MDP) conditioning.

Methods: Various models were created for tetragonal zirconia crystals, molecular MDP, and MDP complex, and tetragonal zirconia crystal. Thermodynamic methods were used to analyze configuration between MDP and tetragonal zirconia crystal through calculation of their Gibbs free energy values and equilibrium constants.

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The present work examined the effects of dipentaerythritol penta-acrylate phosphate (PENTA) as an alternative phosphate ester monomer for bonding of methacrylate-based resins to yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and further investigated the potential bonding mechanism involved. Shear bond strength testing was performed to evaluate the efficacy of experimental PENTA-containing primers (5, 10, 15, 20 or 30 wt% PENTA in acetone) in improving resin-Y-TZP bond strength. Bonding without the use of a PENTA-containing served as the negative control, and a Methacryloyloxidecyl dihydrogenphosphate(MDP)-containing primer was used as the positive control.

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Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular.

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